1. Field of Invention
The invention relates to, in general, refrigeration and, more particularly, an evaporator and a refrigeration system comprising the evaporator.
2. Description of Related Art
When a refrigeration system, such as the refrigeration system of an air conditioner, is operated in winter and the ambient temperature is very low, the evaporating temperature of the evaporator will be less than zero degrees, and, consequently, the refrigeration system needs to be defrosted. With the conventional refrigeration system, full reverse circulation is used for defrosting; that is, the condenser is used as an evaporator, and the evaporator is used as a condenser.
With the conventional refrigeration system, when defrosting is performed, the indoor ambient temperature will be reduced, thus causing comfort degree to be reduced. On the other hand, defrosting will cause indoor-environment-heat supply to be broken off, thus reducing the energy efficiency of the system.
In addition, because refrigerant guide pipes are usually disposed within the inlet header and the outlet header of the evaporator, during defrosting, the flow resistance of the refrigerant is very large, and the refrigerant may not pass through the evaporator in large quantities rapidly such that the defrosting speed is low. In the refrigeration system using a refrigerant (for example, R407C with large temperature glide), because the frosted position is usually adjacent to the refrigerant inlet of the heat exchanger, defrosting may not be rapidly performed by “reverse-circulation defrosting” mode of introducing the gaseous refrigerant from the outlet header such that the defrosting time is long and the operating efficiency of the system is low.